ViewSonic V3D231 3D Monitor Review

Passive vs. Active 3D Technology

While there are more possible ways of achieving the effect, the two main approaches consumer electronic manufactures use to transform a two-dimensional image into what appears to be a three-dimensional one are based on one of the oldest methods known: stereoscopy. This technique relies on fooling the brain by presenting a different 2D picture to each eye and then having the brain perform the trick of turning them into one three dimensional composite image.

The human eyeball is a remarkable organ, but by itself it actually does a poor job of creating a viable 3D image of your surroundings. Thankfully—or at least thanks to natural selection—we have two eyes mounted slightly apart on the same horizontal plane. The difference in perspective between the left and right gives enough visual clues for our brain to weave an accurate 3D image from the 2D images. This is why one-eyed people may have some depth perception but not all that much compared to those of us blessed with binocular vision.

In the old days, fooling the brain into thinking it was seeing a 3D image was usually accomplished by placing two very similar yet subtly different images side by side and physically blocking each eye from seeing the other image. With traditional stereoscopy, 2D photographs are shot from slightly different angles so the viewer’s brain interprets the result as one 3D image. If you’ve ever looked at an aerial photo through a stereoscope, you may have been startled (and pleased) to find buildings poking up like tiny Lego creations from a perfectly flat piece of paper. Nowadays this effect is all achieved by electronics, and while the nuts and bolts differ the end result is the same: a 3D image from a 2D imaging device.

The dominant solution for creating the 3D sensation on the PC is NVIDIA’s 3D Vision, an active 3D technology. The viewer wears a pair of LCD shutter glasses mounted in a typical eyeglass frame that rapidly opens the left lens while making the right opaque and vice-versa 120 times per second, all the while staying in synch to the unique left/right images being flashed on the screen. This works fairly very well, particularly since NVIDIA has been constantly updating their driver stack to support the latest titles. Unfortunately, the glasses are expensive so they need power to work and the solution runs directly off of the GPU, adding a substantial amount of performance degradation. 3D Vision is also proprietary technology, so you will need an NVIDIA GPU as well as a compatible 120Hz LCD monitor. In addition, first generation models suffered from halved refresh rates, halved perceived brightness levels, and crosstalk (ghosting) between the left and right sides. The second generation has overcome most of these negatives via increased refresh rates, backlight brightness boosting when in 3D mode, tweaks to the glasses, and other refinements. The end result is a much improved image that is no darker than a 2D image with almost no ghosting. Unfortunately, battery life is still an issue, and the glasses are still quite expensive.

The second method of accomplishing a stereographic image is passive 3D. In this method the LCD monitor has special polarization layers that take every other horizontal line and focus the light waves out at a certain orientation—usually 45° and 135°. When this technique is used in conjunction with specially polarized glasses, the left eye only sees the left image and the right only sees the right image. Since the active technology is in the monitor itself, passive 3D glasses are inexpensive and lightweight, and they don’t require batteries. When properly executed, passive 3D can create a seamless, flicker-free 3D field of vision thanks to the fact that both the left and right images are displayed at the same time. Furthermore, you are not tied into one GPU manufacturer: Intel and AMD video cards will work just as well as NVIDIA products.

The downsides are that there is still usually some crosstalk / ghosting / color halo’ing as the fact remains to keep the 3D “sweet spot” larger than a postage stamp the two polarizing angles can not be too severe. Also while there is indeed no flickering like with active NVIDIA first generation setups, the image is noticeably darker than 2D images (thanks to the polarization of the back light). It is also noteworthy that the side effect to this setup is you are in essence turning a 1080p image into what is seen by your eyes as a 1080i / 540p 3D image.

For many consumers, the issues with passive 3D will be minor obstacles, but while this technology has the potential to be as good in games as NVIDIA’s active setup, the reality is quite different. NVIDIA has and still is spending enormous amounts of time and effort to make their 3D setup as seamless and user-friendly as possible. In other words, active 3D “just works” when it comes to games and other applications. The same cannot be said of passive setups because the software is not made by the hardware maker but by a third party, in Viewsonic’s case, Dynamic Digital Depth Inc. and their TriDef software technology. This means that results can vary from good to dreadful, with numerous issues from gun sights in FPS games not working properly to only half of in-game text or movie subtitles being displayed.

Of course, only you can decide whether active or passive 3D is right for you—or whether you prefer to stick with tried and true 2D displays. At present, neither technology is fully mature, and each has its own set of strengths and weaknesses.

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